Patent specifications U.S. Pat. No. 5,625,661, U.S. Pat. No. 6,256,369 B1 and the utility model specification DE 299 23 967 U1 from the applicant, the entire contents of which are hereby incorporated herein by reference, disclose computed tomography units that have X-ray tubes with jumping foci.
U.S. Pat. No. 5,625,661 indicates a CT unit in which the focus can jump in the z-direction to a number of different focal positions relative to the X-ray tube so that, in accordance with the variation in the focal position in conjunction with an identical multirow detector situated opposite, a number of beam paths are produced that result in improved scanning of an examination object. The displacement of the focal position of the jumping focus takes place in this case exclusively in the z-direction, the course of the beam remaining unchanged in the radial or azimuthal direction.
Patent specification U.S. Pat. No. 6,256,369 B1 likewise discloses a CT unit with a jumping focus, an X-ray tube also being shown here in FIG. 1, whose jumping focus moves in the xy-plane at a constant distance from the detector, that is to say perpendicular to the system axis. No movement takes place here in the radial direction.
Finally, the utility model specification DE 299 23 967 U1 exhibits different variants of a CT unit with a jumping focus, a displacement in the radial direction also being shown here in addition to the displacements of the focus in the xy plane and in the z-direction.